Apparatus for signal recording on insulators

ABSTRACT

Apparatus for the recording of transmitted information in which an input signal is caused to illuminate a photoconductive control member in patterned form to produce a conductivity pattern in the control member which controls the deposition of electrostatic charge on the surface of a dielectric recording member in contact with the control member. A further photoconductive layer contained as a substrate on the dielectric recording member is used to discharge residual image charges on the dielectric recording member after the image has been developed and transferred.

United States Patent 1 Matkan [451 July 17, 1973 1 APPARATUS FOR SIGNAL RECORDING 0 INSULATORS [75] lnventor: Josef Matkan, Malvern, Australia [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan [22] Filed: Nov. 11, 1971 [211 App]. No.: 197,866

[30] Foreign Application Priority Data Nov. 13, 1970 Australia 3189/70 [52] US. CL... 346/74 ES, 178/66 A, 10l/DIG. 13,

346/74 CR [51] Int. Cl. Gold 15/06, G03g-15/00 [58] Field of Search. 346/74 ES, 74 CR; v 355/3; IOIIDIG. 13; 178/66 A [561 References Cited UNITED STATES PATENTS 3,323,131 5/1967 MacGriff ..346/74 ES 3,609,031

9/1971 Kinoshita 346174 ES 3,659,936 5/1972 Klose et al. 346/74 ES 3,368,106 2/1968 Berthold 346/74 CR 3,681,527 8/1972 Nishiyama 346/74 ES FOREIGN PATENTS OR APPLICATIONS 755,486 8/1956 Great Britain 346/74 ES Primary ExaminerStanley M. Urynowicz, Jr. Attorney-Joseph M. Fitzpatrick, John Thomas Celia et al.

[57] ABSTRACT Apparatus for the recording of transmitted information in which an input signal is caused to illuminate a photoconductive control member in patterned form to produce a conductivity pattern in the control member which controls the deposition of electrostatic charge on the surface ofa dielectric recording member in contact with the control member. A further photoconductive layer contained as a substrate on the dielectric recording member is used to discharge residual image charges on the dielectric recording member after the image has been developed and transferred.

2 Claims, 4 Drawing Figures YPAIENIED I --3.747.119

SHEU 2 [If 2' APPARATUS FOR SIGNAL RECORDING ON INSULATORS This invention refers to signal recording and in particular refers to a method in which a photoconductor is used to control the impression of a latent image charge on a dielectric surface.

BACKGROUND OF THE INVENTION Prior art signal recording methods are known in which an input signal is used to produce a light pattern which in turn controls the discharge of a charged photoconductor surface. It is also known to use a light pattern on a screened photoconductor to modulate the passage of charged ink powder through said screen to deposit said ink power in patterned form on a paper sheets or the like positioned on the opposite side of said screen. A light pattern impressed on a photoconductor may also be usedto modulate thecharge impressed on an insulating surface in contact with said photoconductor. The thus produced electrostatic latent image on said insulator surface may be developed thereon to form a permanent recond, and in addition the developed image may be transferred to a receiving member other than said insulator surface is required. Said receiving member may be a sheet of paper or the like. Provided a method is available for the removal of residual charge from the insulator surface the insulator surface may then be used to record further information.

SUMMARY OF THE INVENTION This present invention teaches a method whereby an image corresponding to an input signal may be recorded as an electrostatic charge pattern on an insulating surface, and such electrostatic charge pattern may be developed by contacting said charged insulating surface with an electrostatic toner material, which toner dispersed toner such as are well known in the art of electrophotographic office copying. The developed image may be transferred to a paper web or the like and fixed to form a permanent record. In this present invention the insulating image recording member is backed with a photoconductor, which photoconductor may be rendered conductive by exposure to light after transfer of the developed image, thereby allowing'discharge to ground of residual charges on said insulating surface when said insulating layer is subjected to an AC or DC potential.

The present invention also utilizes a photoconductor to modulate the charged pattern produced on the insulator surface, the image .control photoconductor being contained as a surface coating on a transparent conducting electrode, which electrode may be connected to one terminal ofa DC power supply. Said image control means is positioned with the photoconductor surface in contact or near contact with the image recording insulator surface, which insulator surface is backed with a further photoconductor layer, this photoconductor layer being backed with a conducting layer which is connected to the opposite terminal of the DC power supply and grounded. The image recording member is preferably in the form of a drum or a belt which form allows the image recording surface to be progressively moved from the image receiving position to a developing position, followed by a transfer position and a cleaning position. The image control means may also g 1 material may be a dry electroscopic powder or a liquid be movably mounted if desired in order to eliminate relative motion between the two contacting surfaces at the time of image impression.

STATEMENT OF INVENTION This present invention thus utilizes a photoconductive control member to define the areas on a dielectric recording member which are charged to form an electrostatic latent image corresponding to the transmitted information to be reproduced, said photoconductive control member consisting of a transparent support having coated thereon a transparent conductive layer which forms a backing electrode, said transparent backing electrode being further coated with a photoconductive layer. Patterned light exposure of said control member introduces a conductivity pattern in the photoconductor layer of said control member which allows selective charging of areas on the surface of the dielectric recording member in contact with the surface of said control member when an electric field is established between the backing electrode of the control member and the conductive backing of the dielectric recording member. The dielectric recording member also contains a photoconductive layer between the dielectric layer and the conductive backing to allow discharge of the residual surface charges on the surface of the dielectric recording member after development and transfer of the image. 1

In a first embodiment of this invention the image control means consists of a conductive transparent backing such as a glass plate coated on one side thereon with a layer of cadmium or tin oxide or other transparent conducting material, which conductive layer is further coated with a photoconductor layer such as photoconductive cadmium sulfide or the like, said photoconductor layer being preferably but not necessarily formulated to be incapable of supporting an electrostatic charge on its surface. A light transmitting means is positioned in contact or near contact with the transparent backing member of said image control means, said transmitting means consisting for instance of a linear array of photodiodes or the like, a fibre optic array containing that number of elements per inch corresponding with the line spacing of the input control signal, or a thin window cathode ray tube or cathode ray tube v with a fibre optic face plateor the like.

trol means, which photoconductor layer is furthercoated with a dielectric layer such as a polyester film or the like. A high voltage power supply is connected so that its positive output is applied to the transparent conducting layer on the transparent backing of the image control means and the negative output is applied to the conductive backing of the image recording drum. The image control means is exposed to a light pattern undulated by the information signal simultaneously with the application of a potential of volts to5 kilovolts or more or less depending on the characteristics of the photoconductors employed from the high voltage power supply, the modulated light pattern causing an electrostatic charge to be deposited on the dielectric surface of the image recording member in those areas corresponding to the light pattern which renders conductive those areas of the photoconductor image control means which are exposed to the light pattern. Thus a modulated pattern of positive electrostatic charge is formed on the dielectric surface of the image recording member corresponding to the light pattern impressed by the input information signal.

The image recording member is rotated at a speed compatible with the frequency of the input signal and thus areas of its surface move in turn to a developing location where dry or liquid dispersed toner material is deposited on the surface in accordance with the charge pattern thereon, followed by a transfer location at which the developed image is transferred to a sheet of paper or other material as desired. Excess developer is then removed and residual electrostatic charges removed from the dielectric surface by the simultaneous application of light and an AC or negative corona. The mechanism of discharging a photoconductive printing element consisting of a photoconductive layer such as for instance cadmium sulfide or the like deposited over a conductive backing having an insulating overlay on its surface remote from said backing by simultaneous application of light and AC or DC of the opposite polarity to that contained on said insulating overlay is prior art and is fully described in U.S. Pat. Nos. 3,438,706 and 3,536,483. The thus cleaned recording member surface may then be reused when required.

In a second embodiment of this invention the dielectric surface is uniformly charged prior to contacting the image control means, and an AC potential or DC potential opposite in polarity to said uniform charge is used in combination with the modulated light to dis charge selected areas on said dielectric surface.

In a third embodiment of this invention the image control means is also in the form of a drum rotating at the same peripheral speed as the image recording memher.

In addition the image recording member may be in the form of an endless belt, or other mechanical configuration if desired to facilitate positioning of the various system components.

In order that the invention may be more readily understood, reference will now be made to the drawings.

BRIEF DESCRIPTION OF DRAWINGS FIGS. 1 and 2 illustrate embodiments in which the control member is stationary,

FIGS. 3 and 4 illustrate embodiments in which the control member is moved at the same peripheral speed as the dielectric recording member.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIG. I the image control member is prepared by applying to a transparent support memher I a transparent conductive layer 2, over which is coated a photoconductive layer 3. A modulated light exposure means 4, consisting of either a photodiode linear array or a fibre optics linear array is positioned in nominal contact with transparent backing member 1. The input to the photodiode or fibre optics array 4 is controlled by signal operated switches 5, to produce by selective exposure areas of differing conductivity on photoconductor layer 3 on the image control member. A conductive drum 6, which can rotate in the direction shown, is coated on its outer surface with a photoconductor layer 7. The photoconductor layer 7 is further coated with a dielectric layer 8. The transparent conducting layer 2 of the image control member is connected to one terminal of a high voltage power supply 9, the other high voltage terminal of this power supply being grounded and in addition connected to the conductive drum 6. In FIG. 1 transparent conductor 2 is connected to the positive terminal of power supply 9, with the negative terminal of said power supply being connected to drum 6 and grounded, but it will be realised that these connections may be reversed if desired, depending on the nature of the image control photoconductor 2, the polarity of the developer, and whether facsimile or reversal reproduction of the transmitted information is required. When power supply 9 is activated and an input signal causes light emission from array 4, those areas of photoconductor 3 which are illuminated will become more conductive than the nonilluminated areas, allowing imagewisc electron flow to occur which produces an electrostatic latent image on dielectric layer 8.

As drum 6 rotates the latent electrostatic image is brought into contact with an electroscopic material at developing station 10. The developer applied may be either a dry toner or a liquid dispersed toner such as is well known in the art of office copying, and the toner may be negative acting or positive acting as desired.

After development the developed image deposit is transferred to a paper web or other desired receptor surface. A roller 13, connected to one terminal of a H.T. power supply 19, is spaced apart from the dielec tric surface 8 of drum 6 a sufficient distance to allow a paper web 11 to contact each surface. In FIG. 1 a roll feed device is illustrated, consisting of a roll of paper 12, conducting transfer roller 13, guillotine l4 and exit tray 15. Roller 13 is shown to be connected to the positive terminal of power supply 19, but it will be realised that if the toner used is attracted to a negative charge then roller 13 will be connected to the negative termi nal of power supply 19. 1

After transfer of the image from dielectric surface 8 to web 11, further rotation of drum 6 occurs and each area of dielectric layer 8 passes through the discharging station, which station consists of a light source 16, corona generating means 17 and discharging power sup ply 18. The application of an AC corona potential or DC corona potential of opposite sign to that initially used for imaging while light. source 16 is energised causes complete discharge of dielectric surface 8.

Referring now to FIG. 2, in which the linear array 4 of FIG. 1 has been replaced with a cathode ray tube 24, the image control member consists of transparent support 21, transparent conductor 22 and photoconductor 23, while the image recording member consists of conducting drum 26, photoconductor layer 27, and dielectric layer-28. High tension power supply 29 is connected between transparent conductor 22 and drum 26, and grounded on the side connected to drum 26. Developing station 30 supplies dry or liquid dispersed toner to develop the latent electrostatic image, which developed image is transferred to paper sheet 33 under the influence of a transfer potential applied to roller 31 from HT power supply 32. Plates 34 and 35 are paper guides, and tray 36 receives the finished copies of transmitted information. Residual charge elimination is carried out by the use of light source 38, corona generating means 37 and discharging power supply 39.

Cathode ray tube 24 may be either of the thin window type, or of the fibre optics face plate type, energised by the input signal to produce by exposure a conductivity pattern in photoconductor 23 which controls charge formation on dielectric surface 28.

In FIG. 3 the image control member is cylindrical in form, consisting of transparent cylinder 41, transparent conductive coating on said cylinder 42, and photoconductor layer 43, rotatably mounted. The recording member consists of conducting drum 46, photoconductor layer 47 and dielectric layer 48. An array of photodiodes or a linear fibre optics array 44 is positioned within the image control drum, in nominal contact with the inner surface of said drum, facing the dielectric recording member at the line of contact between the two drums. The drums are rotated towards each other at equal peripheral speeds. Developing, image transfer and discharging are as in FIG. 1 of FIG. 2.

In FIG. 4 a cathode ray tube 54 is used instead of photodiode or fibre optics array of FIG. 3. In this instance the image control member consists of transparent support cylinder 51, transparent conductor 52 and photoconductor layer 53. The recording member consists of conductive cylinder or drums 56, photoconductor layer 57 and dielectric layer 58. Developing, image transfer and discharging are as in FIG. 1 or FIG. 2.

To add further to the understanding of this invention reference will now be madeto the following examples:

EXAMPLE 1 This example uses the apparatus of FIG. 1. The image control member comprised a glass plate 1 mm. thick, having coated thereon on one side a transparent layer of cadmium oxide, to which layer electrical connection was made. The photoconductor layer consisted of photoconductive cadmium sulfide in an insulating polyester resin binder, pigment/binder ratio 4 l.

A linear fibre optics array was positioned in contact with the glass backing of the image control member,

this array consisted of 0.125 mm. fibres at 0.250 m.m.

spacing. The other end of the fibre array terminated in a linear to circular'converter whereby light could be fed into selected fibres in response to an input signal. Electrical connection to the conductive layer of the image control member was made as in FIG. I that is the conductive layer of the image control member was con nected to the positive terminal of a high voltage power supply, the negative terminal of said power supply being connected to the aluminium cylinder of the recording member and grounded. A voltage of 500 volts was applied simultaneously with the transmission of the image input signal, and the resultant conductivity pattern in the photoconductor layer of the image control 'member allowed selective charging of the dielectric surface of the recording member. The image charge was adequate for development with a negative acting liquid dispersed toner of the type used in office copying EXAMPLE 2 The fibre optics array of Example 1 was replaced with a linear photodiode array, energised selectively by input Signals.

EXAMPLE 3 The fibre optics array of Example 1 was replaced with a thin window cathode ray tube.

EXAMPLES 4 6 The stationary image control member of Examples 1 3 was replaced with a rotating image control member, in which a thin walled glass cylinder, 5 inches outside diameter was coated on its outer surface with a transparent conducting layer of cadmium oxide, which was .further overlain with a layer of photoconductive cadmium sulfide in an insulating resin binder.

EXAMPLES 7 12 The cadmium sulfide photoconductive substrate of the recording member of Examples 1 6 was replaced with a layer of vitreous selenium, and the imaging polarity was reversed.

I claim:

1.- An apparatus for producing a visible copy of transmitted information comprising a recording member consisting of a conductive base having coated thereon a photoconductive layer overlaid with a layer of dielectric material, an image control member consisting of a transparent base having coated thereon a transparent conducting layer over which is coated a photoconductive layer, said photoconductive layer of said image control member being in line contact with said dielectric layer of said recording member, a signal responsive light emitting means disposed in line contact with said transparent base of said image control member, means for forming an electrostatic latent image by establishing a directional electrostatic field between said image control member and said recording member simultaneously with-the application of a signal to the signal responsive light emitting means to'form an electrostatic latent image on said dielectric layer of said recording member, means for developing the thus formed electrostatic latent image by application of electroscopic marking particles thereto, means for transferring the developed image onto transferring material, and cleaning means for removing the residual electrostatic image on said recording member by the simultaneous application of light and an electric field opposite in polarity to that of said directional electrostatic field.

2. The apparatus for producing a visible copy of transmitted information according to claim 1. wherein said image control member and said recording mem her are cylindrical in form and rotate in contact with each other at the same peripheral speed.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3(747'1l9 Dated J 973 Inventor(s) JOSEF MA'IKAN It is certified that rror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col unm' l, line 16, "pqwer" should read -powder; Column line 25,- "is" should read -if-;-;

2 "Fig;- 1 Of Fig 2" shquld read Figv. 1 or Signed and isczfale c} this 27th day of November 1973 J (SEAL) Atte'st:

EDWARD M.-FLETCHER,JR. i K RENE'D. TEGTMEYER At test ing Officer Acting Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I Patent No. 9 Dated J ly 17, 1973 Inventor-(s) JOSEF MATKAN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 16, "power" should read powder; Column 1, line 25,- "is should read if-W;

Column 5, line 15 "Fi l of Pi 2" I I g 2. I 9,v g shonld read F g. l or Signed and sealed this 27th da of November 1973.

I (SEAL) Attest:

EDWARD MTLETCHERJR. RENE D. TEGTMEYER ttestl ng Off cer Acting Commissioner of Patents 

2. The apparatus for producing a visible copy of transmitted information according to claim 1, wherein said image control member and said recording member are cylindrical in form and rotate in contact with each other at the same peripheral speed. 